test: Add unit test coverage for Init and Shutdown code

Currently this code is not called in unit tests. Calling should make it
possible to write tests for things like IPC exceptions being thrown during
shutdown.

src/common/args.cpp

@@ -589,6 +589,14 @@ void ArgsManager::AddHiddenArgs(const std::vector<std::string>& names)
     }
 }
 
+void ArgsManager::ClearArgs()
+{
+    LOCK(cs_args);
+    m_settings = {};
+    m_available_args.clear();
+    m_network_only_args.clear();
+}
+
 void ArgsManager::CheckMultipleCLIArgs() const
 {
     LOCK(cs_args);

src/common/args.h

@@ -359,11 +359,7 @@ protected:
     /**
      * Clear available arguments
      */
-    void ClearArgs() {
-        LOCK(cs_args);
-        m_available_args.clear();
-        m_network_only_args.clear();
-    }
+    void ClearArgs();
 
     /**
      * Check CLI command args

src/netbase.h

@@ -121,6 +121,13 @@ public:
         m_reachable.clear();
     }
 
+    void Reset() EXCLUSIVE_LOCKS_REQUIRED(!m_mutex)
+    {
+        AssertLockNotHeld(m_mutex);
+        LOCK(m_mutex);
+        m_reachable = DefaultNets();
+    }
+
     [[nodiscard]] bool Contains(Network net) const EXCLUSIVE_LOCKS_REQUIRED(!m_mutex)
     {
         AssertLockNotHeld(m_mutex);
@@ -142,9 +149,9 @@ public:
     }
 
 private:
-    mutable Mutex m_mutex;
-
-    std::unordered_set<Network> m_reachable GUARDED_BY(m_mutex){
+    static std::unordered_set<Network> DefaultNets()
+    {
+        return {
             NET_UNROUTABLE,
             NET_IPV4,
             NET_IPV6,
@@ -153,6 +160,10 @@ private:
             NET_CJDNS,
             NET_INTERNAL
         };
+    };
+
+    mutable Mutex m_mutex;
+    std::unordered_set<Network> m_reachable GUARDED_BY(m_mutex){DefaultNets()};
 };
 
 extern ReachableNets g_reachable_nets;

src/rpc/server.cpp

@@ -323,6 +323,12 @@ void SetRPCWarmupStatus(const std::string& newStatus)
     rpcWarmupStatus = newStatus;
 }
 
+void SetRPCWarmupStarting()
+{
+    LOCK(g_rpc_warmup_mutex);
+    fRPCInWarmup = true;
+}
+
 void SetRPCWarmupFinished()
 {
     LOCK(g_rpc_warmup_mutex);

src/rpc/server.h

@@ -30,6 +30,7 @@ void RpcInterruptionPoint();
  */
 void SetRPCWarmupStatus(const std::string& newStatus);
 /* Mark warmup as done.  RPC calls will be processed from now on.  */
+void SetRPCWarmupStarting();
 void SetRPCWarmupFinished();
 
 /* returns the current warmup state.  */

src/test/CMakeLists.txt

@@ -63,6 +63,7 @@ add_executable(test_bitcoin
   net_peer_eviction_tests.cpp
   net_tests.cpp
   netbase_tests.cpp
+  node_init_tests.cpp
   node_warnings_tests.cpp
   orphanage_tests.cpp
   pcp_tests.cpp

src/test/net_tests.cpp

@@ -702,6 +702,7 @@ BOOST_AUTO_TEST_CASE(get_local_addr_for_peer_port)
 
 BOOST_AUTO_TEST_CASE(LimitedAndReachable_Network)
 {
+    g_reachable_nets.Reset();
     BOOST_CHECK(g_reachable_nets.Contains(NET_IPV4));
     BOOST_CHECK(g_reachable_nets.Contains(NET_IPV6));
     BOOST_CHECK(g_reachable_nets.Contains(NET_ONION));

src/test/node_init_tests.cpp

@@ -0,0 +1,49 @@
+// Copyright (c) 2025 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <init.h>
+#include <interfaces/init.h>
+#include <rpc/server.h>
+
+#include <boost/test/unit_test.hpp>
+#include <test/util/setup_common.h>
+
+using node::NodeContext;
+
+BOOST_FIXTURE_TEST_SUITE(node_init_tests, BasicTestingSetup)
+
+//! Custom implementation of interfaces::Init for testing.
+class TestInit : public interfaces::Init
+{
+public:
+    TestInit(NodeContext& node) : m_node(node)
+    {
+        InitContext(m_node);
+        m_node.init = this;
+    }
+    std::unique_ptr<interfaces::Chain> makeChain() override { return interfaces::MakeChain(m_node); }
+    std::unique_ptr<interfaces::WalletLoader> makeWalletLoader(interfaces::Chain& chain) override
+    {
+        return MakeWalletLoader(chain, *Assert(m_node.args));
+    }
+    NodeContext& m_node;
+};
+
+BOOST_AUTO_TEST_CASE(init_test)
+{
+    // Reset logging, config file path, rpc state, reachable nets to avoid errors in AppInitMain
+    LogInstance().DisconnectTestLogger();
+    m_node.args->SetConfigFilePath({});
+    SetRPCWarmupStarting();
+    g_reachable_nets.Reset();
+
+    // Run through initialization and shutdown code.
+    TestInit init{m_node};
+    BOOST_CHECK(AppInitInterfaces(m_node));
+    BOOST_CHECK(AppInitMain(m_node));
+    Interrupt(m_node);
+    Shutdown(m_node);
+}
+
+BOOST_AUTO_TEST_SUITE_END()

src/test/util/setup_common.cpp

@@ -214,7 +214,10 @@ BasicTestingSetup::~BasicTestingSetup()
     } else {
         fs::remove_all(m_path_root);
     }
+    // Clear all arguments except for -datadir, which GUI tests currently rely
+    // on to be set even after the testing setup is destroyed.
     gArgs.ClearArgs();
+    gArgs.ForceSetArg("-datadir", fs::PathToString(m_path_root));
 }
 
 ChainTestingSetup::ChainTestingSetup(const ChainType chainType, TestOpts opts)